Retractable safety landing for an access tube



June 12, 1962 W. W. DA LEE ETAL RETRACTABLE SAFETY LANDING FOR AN ACCESSTUBE Filed Feb. 18, 1960 4 Sheets-Sheet 1 FIG. 1

' IN V EN TORS HARRY w. THOMAS BY WILLIAM wgDALEE WILSON, LEWIS 8: MRAEATTORNEYS June 12, 1962 w. w. DA LEE ETAL RETRACTABLE SAFETY LANDING FORAN ACCESS TUBE 4 Sheets-Sheet 2 Filed Feb. 18, 1960 FIG. 3

INVENTOR.

HARRY w. THOMAS BY WILLIAM w. DALaEE WILSON LEWIS a MRAE ATTo RNEYs W.W. DA LEE ETAL June 12, 1962 RETRACTABLE SAFETY LANDING FOR AN ACCESSTUBE 4 Sheets-Sheet 5 Filed Feb. 18, 1960 FIG.?

INVENTOR. FIG. 5 HARRY w. THOMAS y WILLIAM w. DALEE WILSON, LEWIS a MRAEATTORNEYS June 12, 1962 RETRACTABLE SAFETY LANDING FOR AN ACCESS TUBEFiled Feb. 18, 1960 4 Sheets-Sheet 4 INVENTOR.

EE M MLR A c 0 H Twa WMW M ML... HWW 8 M w ATTORNEYS nited States atentfi gun Filed Feb. is, was, Ser. No. 77 5 claims. or. 182--83) Thisinvention relates to a retractable safety landing and more particularlyto a safety landing positioned in adownwardly extending access tube toprevent a person within such tube from slipping and falling the entirelength of the tube.

As used in the description of the present invention, the term accesstube refers to the entrance passage or shaft leading from the surface ofthe ground to an underground facility such as a mine, shelter, sewagelif-t station, a pumping, metering or junction station for water,natural gas or electricity and the like.

State and local health departments have become in creasingly aware ofthe danger of serious injury involved in accidental falls within accesstubes. Due to the human factors involved, falls cannot be entirelyeliminated. However, the extent of the injuries resulting from suchfalls can be greatly reduced if proper preventive safety measures areemployed.

One proposed method for reducing the seriousness of falling injuries isto provide platforms at spaced intervals in the tubes so that if aworkman does fall, he can only fall a maximum predetermined distance.One proposed platform spacing specification calls for a platform atleast every fifteen feet. A fall of fifteen feet is serious, but is notusually as damaging as a fall of twenty-five or thirty feet.

The provision of permanent platforms in the tubes is one obviousexpedient. However, in the use of permanent platforms, an opening largeenough for a man to pass through must be provided in the platformdiametrically opposite the descent ladder to permit passage by theplatform. With this technique, if the man does fall off the ladder hewill normally fall on the portion of the platform adjacent the ladder.There is, however, some danger that he will travel across the tube,during his fall, to the opposite side of the tube and through theopening of the platform or accidentally fall through the opening when heturns on the platform preparatory to descending to the next level. Theuse of such platforms requires that the cross-sectional area of the tubebe considerably enlarged to provide room for the platform plus opening.A tube having a small crosssectional area is desirable as it is saferbecause it acts as a safety enclosure to prevent falls. vFor example,when a conventional thirty-six inch diameter tube is used, the Workercan release his hand hold on the ladder and lean back against the tubewall without falling. Additionally, the fear of falling is considerablyreduced when such small tubes are used. This fear is believed to be acontributing cause for many falls.

According to the present invention, a retractable platform is providedwhich does not require enlargement of the access tube and which willcompletely eliminate the possibility of falling further than theplatform.

It is, therefore, an object of the present invention to provide aretractable safety platform for an access tube.

Another object of the invention is to provide such a platform which isrelatively inexpensive and is easily installed.

A further object of the invention is to provide a foldable safetyplatform which may be positioned intermediate the upper and lower endsof an access tube which requires only a relatively low-cost modificationof the tube.

A still further object of the invention is to modify the access tube bythe provision of an opening in one side wall intermediate the upper andlower ends for the foldable retractable landing.

A further object of the invention is to provide a second retractableplatform usable where two or more platforms are required and which canbe moved to a non-obstructing position by use of the foot of onedescending in the tube, and which is provided with means for automaticclosure to an obstructing position after the workman has passed thereby.

Another object of the invention is to provide catch means to hold theretractable platforms in a non-obstructing position and to provide dualrelease means whereby the catch may be released as soon as the workmanpasses thereby or may be released remotely at a point adjacent theentrance opening.

Another object is to provide, in one embodiment, interlock means for amulti-landing installation whereby when one platform is in the openposition, the other is automatically moved to the closed position.

Other objects of this invention will appear in the following descriptionand appended claims, reference being had to the accompanying drawingsforming a part of this specification wherein like reference charactersdesignate corresponding parts in the several views.

In the drawings:

FIGURE 1 is a side elevational view of a sewage lift station embodyingthe retractable landing of the present invention;

FIG. 2 is a top plan sectional view of the intermediate foldable landingof FIG. 1 on an enlarged scale taken substantially along line 2-2 ofFIG. 1 looking in the direction of the arrows;

FIG. 3 is a sideelevational view in section of the lift station of FIG.1 taken substantially along line 3-3 of FIG. 2 looking in the directionof the arrows;

FIG. 4 is a top plan sectional view of the lower slidable landing ofFIG. 1 on an enlarged scale taken substantially along line 4-4- of FIG.1 looking in the direction of the arrows;

FIG. 5 is a sectional view of the rear platform hinge mounting takensubstantially along line 5-5 of FIG. 2 looking in the direction of thearrows;

FIG. 6 is an enlarged sectional view similar to FIG. 3 showing anembodiment of interlock means;

FIG. 7 is a sectional View of the track and roller arrangement, withinterlock structure attached, taken substantially along line 77 of FIG.2. looking in the direction of the arrows;

FIG. 8 is a view of the roller and track arrangement for the slidablelanding taken substantially along line 88 of FIG. 4 looking in thedirection of the arrows.

Before explaining the present invention in detail, it is to beunderstood that the invention is not limited in its application to thedetails of construction and arrangement of parts illustrated in theaccompanying drawings, since the invention is capable of otherembodiments and of being practiced or carried out in various ways. Also,it is to be understood that the phraseology or terminology employedherein is for the purpose of description and not of limitation.

The use of the present invention Will be described hereinafter inconnection with a sewage lift station 10. It will be readilyappreciated, however, that the invention is capable of application to awide variety of such underground facilities.

Sewage lift stations are provided at predetermined inintervals in sewagelines to pump sewage along its way to the terminal sewage disposalstation. Such lift stations comprise a room 12 buried in the ground andsupported on a concrete pad 13. The room 12 may contain, for example,motors, pumps, control apparatus, internal piping, valves and fittings,sump pump, blower, de-humidifier, internal lighting, power wiring andthe like. In addition to containing this equipment, such rooms are largeenough to accommodate a Serviceman to permit maintenance and repairfunctions. Entrance to the underground room 12 is gained by means of anaccess tube 14 which leads from the surface of the ground 15 to theceiling of the room. A ladder 22 is secured to one wall of the tube 14and extends from the tube entrance opening 24, thorugh the tube exitopening 26 and terminates in the room 12. As shown, foldable safetylanding 30 is provided intermediate the upper and lower ends of the tube14 and a second slidable landing 32 is provided at the lower end of thetube 14.

The number of such landings may be as few as one or as many as needed tomeet safety regulations. The exact number used depends upon the combinedlength of the tube 14 and the depth of room 12. The lowermost landing isa slidable landing such as is described in our copending US. patentapplication, Serial No. 842,263 filed September 25, 1959. Such a landingmay be used if two or more landings are necessary. However, where onlyone intermediate landing is required, it is preferred, according to thepresent invention, to use a foldable landing as will be hereinafterdescribed.

As may best be seen in FIGS. 3 and 4, the lowermost retractable safetylanding 32 is positioned on the ceiling 20 of the room 12 and normallyextends across the lower opening 26 of the tube 14 to obstruct passagethere through. The landing 32 includes a trackway which extends acrossthe opening 26 and thence for a distance along the ceiling. The trackwayincludes a pair of spaced rails 36, 38 which are secured to the ceiling20 by means of brackets 40, 42, 44. The landing platform 34, which maybe a metal grating, is provided with rollers 46 which ride in the rails36, 38. If desired, other anti-friction means, such as slidable shoes,could be used in place of the rollers 46.

As may be seen in FIG. 8, the rails 36, 38 comprise a sidewall portion48 which is secured to the brackets 40, 42, 44. A curved portion 50 isprovided at the lower end of the portion 48 to carry the rollers 46. Anoutwardly extending flange 52 is provided at the upper end of theportion 48 to act as a guard. Each roller 46 is 'rotatably mounted on anaxle 54 which is secured to the underside of the platform 34. Theplatform is provided with a flange 56 which overlaps the rails 36, 38 tocarry the weight of the platform in case the axle or rollers break. Theflange 56 also prevents snagging of a workman descending the ladder.Stop members (not shown) are provided in the rails 36, 38 to limitmovement of the platform 34 therealong. A handle 66 is secured to theunderside of the platform 34 to provide for manual opening of thelanding.

Safety lock means comprising a spring-loaded plunger 68 mounted in acasing 70 are secured to the lower end of the tube 14 at a point justabove the platform 34. A cooperating lug 72 projects upwardly from theplatform 34. When the platform 34 is moved to a nonobstructing positionalong the rails 36, 38, the plunger 68 will engage the lug 72 and holdthe platform in the non-obstructing position. Release means, comprisinga pair of cables 74, 76, extend upwardly from the plunger 68 to permitdisengagement of the lug 72 after climbing above the platform 34. Eachcable 74, 76 includes a pull cable 78 enclosed in a length of tubing 80and having a pull ring 82 at the upper end thereof. One of the releasecables 74 leads to a point above the retractable landing 32 a sufficientdistance to permit actuation thereof by a workman whose feet are atapproximately the same level as the retractable landing. This permitsone who has just climbed above the landing 32 to release the catchmeans. The second release cable 76 leads to a point adjacent to theaccess tube entrance opening 24 to permit remote release of the catchmeans. The second cable 76 is provided to permit closing of the landing32 without descending the tube 14. Such use is desirable for theinstance where a workman has forgotten to close the landing afterleaving the tube or where a second workman wishes to enter the tubeafter the passage of a first workman.

Counterweight means are provided to constantly urge the platform 34 tothe obstructing position. The counterweight means comprises a cable 84which is secured to an arm 58 on the underside of the platform 34 andwound around a pulley 86. The cable 84 is weighted at its lower end bymeans of a weight 88. In operation, when the catch means is released,the counterweight 88 is operative ot move the landing 32 to itsobstructing position. As will be readily appreciated, other suitableclosure means, such as a spring, may be used in place of acounterweight. Additionally, the platform may be power operated to openand close by a motor or pneumatic or hydraulic power means.

The intermediate landing 30, as may be seen in FIGS. 2, 3 and 6,comprises a platform 90 constructed in two sections 92, 94 pivotallysecured together by hinges 96,- 98. The sections 92, 94 may befabricated from any suita" ble material, however, a desirablecombination of lightness and strength was found in the use of areinforced fiber glass material or structural aluminum.

The front platform section 92 is provided with rollers which ride in apair of rails 102, 104 secured tothe tube 14. As may be seen in FIGS. 5and 7, the rails- 102, 104 are substantially the same shape as therailsfor the lowermost landing 32. The rear platform section 94 isprovided with a laterally extending elongated memher to which leaves114, 116 of hinges 106, 108

are secured. The other hinge leaves 118, 120 of hinges 106, 108 aresecured to brackets 122 mounted in the outwardly projecting recess 124of the tube 14.

In operation, as may be seen in FIG. 3, the landing 30 normally assumesa blocking position as illustrated in solid lines. When it is desired topass thereby, the platform sections 92, 94 are folded upwardly and intoand out-of-the-way position into the recess 124 as shown in dottedlines.

The folding movement is accomplished by means of a platform controlmechanism 126. The mechanism 126 comprises a control handle 128pivotally mounted at one end to a bracket 130 positioned approximately:shoulder-high above the landing 30. A connecting rod 132 is pivotallysecured intermediate the ends of handle 128 and extends down one side ofthe tube 14 to a point beneath the landing 30 at which point it ispivotally secured intermediate the ends of a control arm 134. The arm134 extends upwardly at an angle to the elongated member 110 and has aright angle portion 112 which is secured to the backside thereof. Theangle between the arm 134 and member 110 is consequently fixed and doesnot vary as the landing 30 is folded up or down.

In operation, the landing 30 is folded to a non-obstructing position byan upward push on handle 128 which is effective, via the connecting rod132, to pivot the arm 134 upwardly. The arm 134, acting through themember 110, pivots the platform section 94 which in turn carries thesection 92 in a rolling action along the rails 102, 104 to a foldedposition in the recess 124. It will be noted that the arm 134 is offsetfrom the section 94 by the member 110. The function of the offsettingmember 110 is to provide a lever arm about the hinge point 136 wherebythe applied force will be translated into a moment sufficient to pivotthe platform sections 92, 94. As will be readily appreciated, if thesection 94 was not offset the turning force would be applied almostdirectly at the hinge point 136 and would be ineffective to fold theplatforms.

The platform 90 is maintained in the folded-open posi tion by theplatform control mechanism 126. The halldle 128 is received, in itsupper position, in a bracket 138 and is held there by a spring loadedcatch 140. The catch 140 is provided with a release cable 142 which isoperative in a manner similar to the cables 74, 76 provided for thecatch on the lowermost landing 32.

Upon release of the catch 140, the platform 90 will return to anobstructing position as the result of the force of gravity. As will benoted in FIG. 6, the platform 90 is never folded to a point where therollers 1% pass under the hinges 96, 98. If the rollers did travelbeyond this point, the platform would be locked in and on external forcewould have to be applied for its return to an obstructing position.

FIGS. 6 and 7 illustrate an embodiment of interlock means which may beprovided if desired to correlate the opening and closing of the twolandings 30, 32 so that when one landing is open, the other must beclosed.

The interlock system includes a pair of stop members 144, 146 eachposition beneath a landing 30, 32 at one end thereof. The forward end145 of the members 144, 146 is tapered, the top surface 147 isrelatively flat, and the rearward end 149 is also relatively flat. Themembers 144, 146 are interconnected by a rod 148 which extends along oneside of the landings 30, 32. The rod 148 is supported and directed inguides 150, 152. A nut 154 is received on threaded portion 156 providedabove the lower guide 152. A compression spring 158 is positionedbetween the nut 154- and guide 152 to constantly urge the rod 148upwardly. Each platform 34, 90 is provided at its front end with aroller member 160, 162 depending therefrom. The roller 160 of thefoldable platform 90 depends at an angle forwardly therefrom so that itwill assume a substantially vertical positionment when the platform isfolded to a non-obstructing position.

In operation, when the platform 90 is folded to the dotted line positionshown in FIG. 6, the roller 160 will ride up the tapered face 145 ofstop member 144, causing the rod 148 to be depressed and compressingspring 158. The roller 160 will then ride over the top surface 14-7 to apoint beyond the rearward end 149. When the roller 160 has passed overthe stop member 144-, the spring 158 will cause the rod 148 to rise,whereby the rearward end 149 of stop member 144 will abut against roller160 and hold platform 90 in the open position. As will be readilyappreciated, the same locking action will occur when the lower platform34 is moved to the open position.

Depression of the rod 148 during movement of one of the platforms 34, 9tto an open position will cause both stop members 144, 146 to bedepressed and will thus act to release the other platform if it islocked open at the time. Upon release, the platforms will eachautomatically return to a closed position as a result, respectively, ofthe counterweight 88 or the spreading of platform 90.

As may be readily appreciated, other forms of interlocking means may beprovided if desired. For example, electric, hydraulic or pneumatic meanscould be used. However, the mechanical system shown is preferred fromthe standpoint of cost and simplicity of installation and operation.

Having thus described our invention, we claim:

1. In combination, a downwardly extending access tube having an entranceopening at the upper end for passage of a person therethrough; a ladderpositioned in the tube; the wall of the tube being provided with afluid-tight outwardly extending recess at a point below said entranceopening; a foldable safety landing normally extending across the tube atthe level of said recess; said landing including a platform having twosections pivotally secured together; one of said sections extending intosaid recess and being pivotally supported therewithin; a trackwayextending beneath the platform and across the tube; the other of saidplatform sections having anti-friction means which ride in saidtrackway; lever means having an operating handle positioned above theplatform and an operating handle positioned below the platform; saidlever means being operatively connected to said first section to pivotsaid section upwardly; said platform being received within said recesswhen in its folded condition; means to releasably lock said lever meansin a position where said platform is folded to a nonobstructing positionpermitting passage thereby; the folded position of said platform beingsuch that the antifriction means of said second platform section doesnot pass beneath the pivotal connection between the platform sectionswhereby said platform will return to its obstructing position by theforce of gravity upon release of the lever means.

2. In combination, a downwardly existing access tube having an entranceopening at the upper end and an exit opening at the lower end forpassage of a person therethrough; said access tube leading into a spaceat the lower end thereof; a ladder extending from the entrance openinginto the space; a retractable safety landing positioned across the lowerend of the tube to normally obstruct passage thereby; said landingincluding a trackway which extends across the tube exit opening and hasa portion extending outside the periphery of the tube; a platform havinganti-friction means which ride in said trackway; said platform beingmovable from the normal obstructing pos-tiion to a non-obstructingposition on the portion of the trackway outside the tube; latch means tohold the platform in said non-obstructing position; and closure meansconstantly urging the platform to its obstructing position; a secondplatform provided intermediate the entrance and exit openings of theaccess tube; said landing comprising a foldable platform including apair of sections pivotally secured together; a first one of saidsections being pivotally supported adjacent one wall of said accesstube; a trackway extending beneath the platform and across the tube; thesecond of said sections having antifriction means which ride in saidtrackway; and lever means positioned above said intermediate platformand operatively connected to said first platform sections to pivot saidplatform to a non-obstructing position; said lever means beingreleasably lockable to hold said platform in its non-obstructionposition; said platform being operative by the force of gravity toreturn to its obstructing position upon release of said lever means.

3. A device as claimed in claim 2 is further characterized in theprovision of release cables operatively connected to the locking meansfor said two landings; said release cables extending to points above thelandings to permit remote release of the landings.

4. The combination comprising a downwardly extending access the havingan entrance opening at the upper end and an exit opening at the lowerend for passage of a person therethrough; said access tube leading intoa space at the lower end thereof; a ladder extending from the entranceopening into the space; a first retractable safety landing normallyextending across the lower end of the tube to obstruct passage thereby;said landing including a trackway which extends across the tube and hasa portion extending outside the periphery of the tube; a platform havinganti-friction means which ride in said track way; said platform beingmovable from the normal obstructing position to a non-obstructingposition on the portion of the trackway outside the tube; first latchingmeans to hold the platform in said non-obstructing position; and closuremeans constantly urging the platform to its obstructing position; atleast one second landing positioned intermediate the entrance and exitopenings of the access tube; said second landing comprising a foldableplatform normally extending across the tube to obstruct passage thereby;a trackway extending beneath the foldable platform and across the tube;said platform including first and second sections pivotally securedtogether; the first section being pivotally supported adjacent one wallof said access tube; the second of said sections having anti-frictionmeans which ride in said trackway; lever means operatively connected tosaid first section to fold said platform into a non-obstructingposition; second latch means to maintain said intermediate platform inthe folded condition said platform being operative to return to itsobstructing position by the force of gravity upon release of said secondlatch means; said first and Second latch means being interconnected by aresilient member constantly urging said latch means to a lockingposition; a catch member provided on each platform to pass over anddepress its respective latch means when its respective platform is movedto a non-obstructive position; the passage of one catch member withconsequent depression of its latch means being elfective to release saidother platform to return to its normal obstruction position.

5. In combination, a downwardly extending access tube having an entranceopening at the upper end for passage of a person therethrough; a ladderpositioned in the tube; and a foldable safety landing normally extendingacross the tube at a point below said entrance opening to normallyobstruct passage thereby; said landing including a platform having twosection-s pivotally secured together; one of said sections beingpivotally supported adjacent one wall of said access tube; a trackwayextending beneath the platform and across the tube; the other of saidplatform section having anti-friction means which ride in saidtrackways; lever means positioned above the platform and operativelyconnected to said first section to pivot said section upwardly; saidlever means comprising an operating handle pivotally secured above thelanding; linkage connecting said operating handle to a support membersecured to said first platform section at a point adjacent the pivotalconnection of said first section to the access tube; said support memberbeing offset from the first platform section whereby the lever means isoperable to exert an effective movement on the first platform section tocause folding of the platform; the wall of the tube adjacent the firstof said sections having provided with a fluid-tight recess to receivethe platform in its folded condition; means to releasably lock saidlever means in a position where said platform is folded to anon-obstructing position permitting passage thereby; the folded positionof said platform being such that the anti-friction means of said secondplatform section does not pass beneath the pivotal connection betweenthe platform sections whereby said platform will return to itsobstructing position by the force of gravity upon release of the levermeans.

References Iited in the file of this patent UNITED STATES PATENTS292,092 Bleuler Jan. 15, 1884 550,810 Winkopp Dec. 3, 1895 696,693 OlsenApr. 1, 1902 1,349,585 Sauer et al Aug. 17, 1920 2,535,544 McKinley Dec.26, 1950

